Idle Fun

[Gus 5]

still sorting out all cars little probs, but heres one ive had since the old engine was in the motorsport

my car wont idle! it just revs up and down..dies often, seems to happen more often when its warm...i have played with:

ICV(from new car, worked fine in there)

intake boot (as above)

cleaned throttle body (however havent played with TPS, as it has a sh*t load more plugs than the normal 3 pin TPS)

adjusted valves

its a little frustrating stalling everywhere.....i might try find out about the TPS, but any other ideas? my only thought is that having the lumpy cam and light flywheel combined makes it easy to stall....at the mo im idling somewhere round 1k (well sounds like that i cant actually tell) as thats the only way i can get it idle at least some of the time

[Carl 3]

ICM? Your ECU to ICV may be a little funny. Try using another ICM or ECU unit?

[Gus 5]

ICM? the ecu and everything worked fine in the other engine (using same everything). and the engine doing exactly the same thing it did in the other car, which makes me think its something mechanical

[Carl 3]

The two most likely causes of erratic idle are the idle control management (ICV-ECU) and vacuum leaks although I should say the vacuum leak is the most common culprit.

If it's not those problems then it could be the fuel pump delivery, leaking head gasket, incorrect timing, or the camshaft being worn.

Edited July 15, 2005 by ///Carl

[m325i 705]

leaking head gasket

[Gus 5]

and a spare engine available?

not HG.....getting e30zone.co.uk chip burnt with 900rpm redline...think the car simply cant idle at the usual...will find out

fun n games

[Carl 3]

900rpm redline - do you mean 900rpm idle???

I'm assuming you're getting the wild chip then? I've got the mild one and even that has banged my redline up to 7k, still haven't hit the limiter in it yet. Ant said the wild will limit at 7.2k

[BM WORLD 1262]

could be running lean .

try a new afm , or adjusting yours , the spring tension goes stiffer in them with age . sometimes they need to be adjusted richer , click it around one notch on the toothed wheel , mark the original position first .

[Williams BMW 0]

This may seem a dumb question but... upping the rev limiter to 7000rpm seems pointless as HP drops off at about 6000rpm.

[Gus 5]

would not be surprised about lean....have tried fiddling with afm before, but might try spare one

the rev limit upping isnt really for power, just to make 1st gear a bit more usable, and for cornering. and it sounds badass. also do have a fair bit more top end now with mods too, so does help...dyno will tell all!

[petone 0]

This may seem a dumb question but... upping the rev limiter to 7000rpm seems pointless as HP drops off at about 6000rpm.

Yeah but you'll probably find that even with the drop off your still getting more torque than you would if you had changed up to a higher gear, If you had a graph of the torque curve you could work out the best time to change gear.

[Williams BMW 0]

Max torque on my 325 is 4000rpm.

Max BHP is at 5825rpm.

Max torque= max cylinder fill of air/fuel mix.

The reason why it drops off after 4000rpm is there's not enough time for proper cylinder fill on the intake stroke. Twisting force is reduced.

The proper timing of gearchanging is change at max HP to re-engage next gear at max torque, and drive between those two figures.

I'm off topic and away on a tangent now, sorry.

[Guest Andrew]

Max torque on my 325 is 4000rpm.

Max BHP is at 5825rpm.

Max torque= max cylinder fill of air/fuel mix.

The reason why it drops off after 4000rpm is there's not enough time for proper cylinder fill on the intake stroke. Twisting force is reduced.

The proper timing of gearchanging is change at max HP to re-engage next gear at max torque, and drive between those two figures.

I'm off topic and away on a tangent now, sorry.

gus has a 288ish cam

[Carl 3]

Max torque on my 325 is 4000rpm.

Max BHP is at 5825rpm.

Max torque= max cylinder fill of air/fuel mix.

The reason why it drops off after 4000rpm is there's not enough time for proper cylinder fill on the intake stroke. Twisting force is reduced.

The proper timing of gearchanging is change at max HP to re-engage next gear at max torque, and drive between those two figures.

I'm off topic and away on a tangent now, sorry.

Haha, on that theory then I only have a 1000rpm rev band for which to drive in - 4500 and 5500!!!

[Williams BMW 0]

also do have a fair bit more top end now with mods too, so does help...dyno will tell all!

Would be interesting to see dyno figures with those mods.

[Williams BMW 0]

Haha, on that theory then I only have a 1000rpm rev band for which to drive in - 4500 and 5500!!!

Quick driving Carl, have fun,just don't get caught.

[Grant 4]

Why is this a sticky?

[Gus 5]

no idea...wasnt me??

dyno will come once ive got everything sorted